This invention relates to sewing machines and, more particularly, to an adaptive arrangement which regulates the operating instrumentalities of a sewing machine to maintain uniform stitch quality independent of varying parameters.
In recent years, domestic sewing machines have become increasingly automated in operation and increasingly versatile as well. For example, at the touch of a button a sewing machine operator may select any one of a large number of decorative stitch patterns which may then be automatically sewn by the sewing machine. Such a sewing machine is disclosed, for example, in U.S. Pat. No. 3,872,808. Although the sewing is done automatically to reproduce the desired pattern, the operator still retains a certain amount of control which affects stitch quality. For example, the operator can regulate the thread tension, the presser foot force, and the sewing speed. However, if the operator changes certain parameters, such as the type of fabric, the seam thickness, the type and thickness of thread, or the needle, without adjusting the thread tension, presser foot force, or speed, the stitch quality will change. Thus, a certain amount of experimentation, depending upon the skill of the operator, is required to adjust the thread tension, presser foot force, and sewing speed, in order to maintain uniform stitch quality when the above-mentioned parameters are varied.
It is therefore an object of this invention to reduce the skill necessary to operate the sewing machine effectively.
It is another object of this invention to reduce the number of controls on a sewing machine.
It is a further object of this invention to eliminate a large amount of detailed and highly technical instructions.